Japanese unexamined patent application publication No. 2007-72422 discloses a tandem-type image-forming device having a photosensitive member unit that can be integrally and detachably assembled in the casing of the image-forming device, the photosensitive member unit including a plurality of photosensitive members, and a pair of side plates disposed on both ends of the photosensitive members for receiving shafts of the photosensitive members.
However, in the image-forming device described above, the rotating shafts of the photosensitive members may slope in a direction orthogonal to a paper-conveying direction, leading to a reduction in image quality due to distortion in the formed images and the like. Accordingly, shaft-receiving parts provided in the side plates for receiving the shafts of the photosensitive members must be formed with great precision. However, the side plates in this conventional image-forming device are configured of separate members that are symmetrical to each other and, thus, are molded from different dies. Consequently, manufacturing error can easily be introduced into the side plates, causing the rotating shafts of the photosensitive members supported by the side plates to deviate in a direction orthogonal to the paper-conveying direction. The same problem of deviation may occur with parts provided for receiving the shafts of the photosensitive members used in image formation if these parts are detachably assembled in the casing of the image-forming device.